A series of one thousand ovals oriented on a delicate sheet of paper, often coming along with a 25-30 page test booklet full of multiple choice and devilish K-Type questions. Even if it's been a decade since you darkened a classroom, a Scantron sheet can send chills up your spine.

Scantron sheets grew in popularity as a testing aid in the mid-1970s, with the method of data acquisition changing the world of testing by turning exams into multiple guess puzzles. These sheets make modern standardized testing possible, but at what cost? And, do you really have to use #2 pencils to fill out the sheets?

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The "Scantron" data forms are ubiquitous with modern education methods (so ubiquitously that the name is applied to most types of generic, bubble-in data entry form) are derived from a relatively old piece of technology. Scantron test forms are a form of Optical Mark Recognition (OMR), a technique devised in the mid-19th Century. Although they don't look like modern Scantron test sheets, punch tape used for communicating data via telegraph is an early version of OMR technology. OMR scanners and sheets began to be used in testing as early as the the 1930s.

Optical Mark Recognition readers measure the amount of light passing through a sheet, with neatly darkened answer ovals blocking light and sending a signal to the OMR reader.

The Scantron Corporation gained market penetration in the 1970s by selling the readers to schools and university departments for low prices, planning to make a profit by selling the OMR sheets necessary to take the tests.

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The sheets are not cheap — they still hover in the fifteen to twenty cent range. 15 million full-time students are enrolled in the United States alone. This accounts for a large consumption of OMR sheets in higher education if each student uses as few as 10-20 in the course of a semester.

OMR scanning methods make grading considerably easier for a teacher, but it radically changes the way testing is performed, as multiple choice questions best fit this style. Essays, short answer questions, reaction diagrams, and most important of all, partial credit fall to the wayside, leading to personal horror stories of Calculus II and Organic Chemistry exams conducted using only multiple choice questions. The tests also create a divide between classrooms of 20 and lecture halls of 200 by altering the type of test likely to be given, and if grading is performed by an instructor or a scanner. Students do get a chance at revenge, however, as OMR sheets and readers are often used for faculty evaluations.

The testing format also provides a benefit, as they make standardized assessments like the ACT, SAT, and MCAT possible. Several million students take these tests each year, with grading becoming a nigh impossible task without OMR readers.

Do you really need a #2 pencil? #2 pencils are pretty useful to OMR testing for a number of reasons. The spread of numbered pencils ranges from 1 to 4 — a #1 pencil has a softer core, while a #4 features denser core, with the properties dependent on the amount of clay used in making the pencil lead. If you use a #1 pencil (featuring the type of lead inside those giant kindergarten pencils) on a standardized test, the softness of the lead could lead to smudging of your delicately filled answer bubbles when the papers are out of your hands and sorted or transported.

A denser pencil lead produces a lighter mark, causing a problem with answer recognition on some (usually older) OMR readers, as the change in light transmission might not be registered by the reader.

#2 pencils happen to be in the middle of the range of the twenty types of graphite pencils produced (these twenty types fall within in a range of 9B to 9H). The #2 pencil IS a great choice for OMR testing as the lead is not too soft so as to smudge, but not so hard that it creates a light mark. Interestingly, #2 pencils created by different companies often vary in their actual composition, with most #2 pencils falling between a B and HB lead grade.

From my experience on the other side of education, popping a 100% on a Scantron graded test often leads to a second look from a professor or graduate teaching assistant, leaving yourself vulnerable to manual grading even if your hacking plan fools the OMR reader. I wouldn't take the risk — spend the time studying unless you have access to your department's Scantron reader and plenty of time for covert trial and error experimentation.